99 F150 Bogging issue.
 

Hello members. Any help is appreciated on this issue. My 99 F150 4.6 4x4 started bogging a few months back. It is slowly getting worst. It happened after a back yard mechanic installed reverse light under the rear bumper and at the same time I ran the fuel tank really low. So this sent me a wild goose chase trying to figure out what was causing the bogging. This is a list that I have done so far. (By it was throwing a #1 cylinder misfire while bogging)

Fuel filter - replaced
PCM - replaced
MAF - cleaned
# 1 cylinder compression good
Catalytic - good
fuel pressure(while bogging) - good
coil - replaced
spark plugs - new
egr - new
clean fuel injector # 1 cylinder - done.
vacuum tested - good

I did a short test and the is anywhere from 11 - 12.5 volts running through the negative post and ground wire.
Pulled all fuses and relays and minor drops in voltage but nothing over 1 volt.

After I ran some Seafoam through the tank the code didn't show up anymore. Now no codes are coming up.

I am completely stumbled. vv:eyes:

Have you run a compression test on the cylinders?
If it has an electric fuel pump, did you pull the pump from the tank and look at the pre-filter on the pickup tube?

99 F150 Bogging issue.
 

I did a compression test on #1 cylinder only. The spark plug that came out of there was really ash fouled and the the code that was coming up while bogging was #1 misfire.
I like the idea of the pre-filter on the pickup tube. :sign0184: That kinda makes sense because the bogging started when I ran the tank super low.
I did a pressure test when driving and there was slight drop in pressure while bogging like 3-4 psi.

I guess the pre-filter on the pickup tube filters before the in-line fuel filter?

If you have a pre-filter it will be on the pickup tube. The last time I experienced this problem was on a 2000 Ford Focus. The lining of the tank was done poorly and de-laminated and plugged up the pickup. I had to pull the entire pump assembly out and clean it off. Not sure what type of pump assembly you have, but it would be one area I would look at. I would also open the fuel line from the motor to the tank and blow some compressed air through it and see if you get any debris out.

It was the head gasket
 

Pulled the coolant reservoir lid off and had lots of oil in there. Not sure why the vacuum test didn't pick that up!

That's a problem. :sad2: